Commits · 05c2c00f3769abb9e323fcaca70d2de0b48af7ba · Kirill Smelkov / linux

22 Dec, 2020 6 commits

ext4: protect superblock modifications with a buffer lock · 05c2c00f

Jan Kara authored Dec 16, 2020

Protect all superblock modifications (including checksum computation)
with a superblock buffer lock. That way we are sure computed checksum
matches current superblock contents (a mismatch could cause checksum
failures in nojournal mode or if an unjournalled superblock update races
with a journalled one). Also we avoid modifying superblock contents
while it is being written out (which can cause DIF/DIX failures if we
are running in nojournal mode).
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201216101844.22917-4-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

05c2c00f

ext4: drop sync argument of ext4_commit_super() · 4392fbc4

Jan Kara authored Dec 16, 2020

Everybody passes 1 as sync argument of ext4_commit_super(). Just drop
it.
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201216101844.22917-3-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

4392fbc4

ext4: combine ext4_handle_error() and save_error_info() · e789ca0c

Jan Kara authored Dec 16, 2020

save_error_info() is always called together with ext4_handle_error().
Combine them into a single call and move unconditional bits out of
save_error_info() into ext4_handle_error().
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201216101844.22917-2-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

e789ca0c

ext4: remove unnecessary wbc parameter from ext4_bio_write_page · be993933

Lei Chen authored Dec 11, 2020

ext4_bio_write_page does not need wbc parameter, since its parameter
io contains the io_wbc field. The io::io_wbc is initialized by
ext4_io_submit_init which is called in ext4_writepages and
ext4_writepage functions prior to ext4_bio_write_page.
Therefor, when ext4_bio_write_page is called, wbc info
has already been included in io parameter.
Signed-off-by: Lei Chen <lennychen@tencent.com>
Link: https://lore.kernel.org/r/1607669664-25656-1-git-send-email-lennychen@tencent.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

be993933

ext4: avoid s_mb_prefetch to be zero in individual scenarios · 82ef1370

Chunguang Xu authored Dec 04, 2020

Commit cfd73237 ("ext4: add prefetching for block allocation
bitmaps") introduced block bitmap prefetch, and expects to read block
bitmaps of flex_bg through an IO.  However, it seems to ignore the
value range of s_log_groups_per_flex.  In the scenario where the value
of s_log_groups_per_flex is greater than 27, s_mb_prefetch or
s_mb_prefetch_limit will overflow, cause a divide zero exception.

In addition, the logic of calculating nr is also flawed, because the
size of flexbg is fixed during a single mount, but s_mb_prefetch can
be modified, which causes nr to fail to meet the value condition of
[1, flexbg_size].

To solve this problem, we need to set the upper limit of
s_mb_prefetch.  Since we expect to load block bitmaps of a flex_bg
through an IO, we can consider determining a reasonable upper limit
among the IO limit parameters.  After consideration, we chose
BLK_MAX_SEGMENT_SIZE.  This is a good choice to solve divide zero
problem and avoiding performance degradation.

[ Some minor code simplifications to make the changes easy to follow -- TYT ]
Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Reviewed-by: Samuel Liao <samuelliao@tencent.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/1607051143-24508-1-git-send-email-brookxu@tencent.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>